Headspace?
 

Hi,

I'm pretty confused about how a lambic beer should be fermented. I'm fermenting with Wyeast Lambic Blend and Wyeast Roselare. I understand that a pellicle requires oxygen...

-Should headspace therefore be provided to encourage the formation of a pellicle, or does ageing a full carboy without the formation of a pellicle achieve the same effect?

-If a headspace is to be provided, what % of the carboy/demijohn should the headspace occupy?

-If I am to leave a headspace, should air be wafted into the carboy after primary fermentation, so at to supply O2 to the oxygen consuming organisms in these blends?

Thanks,

Delaney

Oxygen doesn't mean headspace, it means micro oxygenation that permeates the carboy/bucket. Headspace will help with acetic character, not Pellicles, in fact a Pellicle will block oxygen in the headspace. That's why the top lambic producers use Better Bottles vs glass carboys because the bugs get a little oxygen to develop flavor

Hmmmm okay, well I am using glass...

so headspace or no?

I am new to sours, but it sounds like the pellicle forms to keep out oxygen. Therefore, you don't need one to get the character from your lacto: the bacteria will still be growing inside. Hopefully someone will confirm.

If I were aging in glass I would try and fill it as full as possible. IMO you will get plenty of oxygenation just by removing the airlock a few times to take gravity/sensory samples over the next few years, oxygen doesnt care if it gets through via the plastic wall of a BB or from a sample thief being plunged into the beer. Brettanomyces is the organism responsible for pellicle formation, but will only form in the presence of oxygen, which is neither good or bad, as it will continue with fermentation regardless...it is just a sign that you are getting oxygenation from somewhere. The thing to watch out for is having too much headspace and a means for oxygen ingress. Acetobacter loves this combo and it will equal your batch turning into vinegar.

Thanks for this.

so does 25% headspace seem like too much?

Not if you're careful...the less the better I imagine.

You want as little headspace as possible. Like any beer, sours will deteriorate in the presence of O2. O2 helps promote acetic acid generation, and also stales the beer. The beer really doesn't need much O2.

Not sure I agree with you on 2 points. 1) Brett is not the only organism in a Sour that forms a pellicle (you are correct that the pellicle is most likely from the Brett), and 2) I'm not sure it only forms a pellicle in the presence of O2. I've had them form in glass fermenters with no leaks (always positive pressure), which had active fermentation and the bung and airlock never taken off.

Headspace is fine in the primary. In the secondary, it should be as small as possible - 25% of a carboy is way too much, you should get it up past where it starts narrowing at least.

However, as it so happens, Lambic is actually the one style that you definitely want to age on top of all the yeast, even for years. In other words, it shouldn't be transferred to a secondary - I ferment my lambics in a glass carboy and leave it there for 1-3 years. So if you do things the "proper" way, headspace is a non-issue, as fermentation will displace all the oxygen.

To answer your other question, pellicles are not needed, nor necessarily even desired. Most of my sours never get a pellicle. A pellicle might be helpful to confirm the beer is adequately inoculated, but you can taste it to determine the same thing, and a perfect process will generally actually prevent a pellicle. So don't worry if you don't see one.

Not universally true. Flemish Reds in particular REQUIRE a constant presence of some amount of oxygen to properly so develop, and it is a fantastic style.